Hope this information helps clarify some of the questions about how to hook sand fleas.
Most folks use a small circle or kahle hook (single hook). Sometimes these are also called "English Hooks".
Hook the sandflea up from underneath about a 1/3 of the way toward the head so the point of the hook is just sticking out through the back of the shell. I prefer my barb exposed.
Top of Flea, head facing left in pictures:
Bottom of Flea, head facing left in pictures:
The second picture shows hooking the flea from under the head.
I've always hooked them from the tail end, through the "key", from the bottom to the top. That was the way taught to me many years ago, and so I have always hooked them from the underside tail end. In retrospect, I do not know which end of the flea is better, or considered right or wrong.
Guess that's one of those things that makes fishing so much fun. The tried and true versus the learning and experimentation. I have never "experimented" with hooking from the front, but may next time I use live fleas.
I found the first two images on another site. The user who made the post I borrowed these images from is "Pier#R". Thanks.
The second two pictures were taken by me using artificial soft plastic fleas from http://www.carolinalures.com
I will try to take and post some better pictures in the near future using real fleas.